This is the result of facebook’s content promotion algorithm, and is clearly an unbelievably, and unambiguously traumatic video that has no valid “free speech” argument, especially when it’s just trolls and terrorists intentionally promoting it to cause trauma.
It is not too much to ask for Facebook to block that - they have no problem blocking media that violates copyright, so the only reason this is still happening is because they don’t actually care. Hell maybe it drives engagement.
Alternatively if they can’t guarantee they’re not good Ng to auto play a baby being beheaded, they can just turn off autoplay and blur all videos. That approach also means there’s no censorship threat, if that’s important to you.